swift—3

import Foundation

//这个版本的 Shape类有些重要的东西不在：一个构造器来在创建实例时设置类。使用 init 来创建一个。

class Shape {

   var numberOfSides = 0

   func simpleDescription() -> String {

        return"A shape with \(numberOfSides) sides."

    }

}

var shape =Shape()

shape.numberOfSides =7

var shapeDescription =shape.simpleDescription()

println(shapeDescription)//A shape with 7 sides.

class NamedShape {

   var numberOfSides: Int = 0

   var name: String

    

   init(name: String) {

       self.name = name

    }   //by gashero

    

   func simpleDescription() -> String {

        return"A Shape with \(numberOfSides) sides."

    }

}

var namedShape =NamedShape(name: "3边形")

namedShape.numberOfSides =3

var namedAhapeDescription =namedShape.simpleDescription()

println(namedAhapeDescription)//A Shape with 3 sides.

class Square:NamedShape {

   var sideLength: Double

    

   init(sideLength: Double, name:String) {

       self.sideLength = sideLength

       super.init(name: name)

        self.numberOfSides =4

       self.name=self.name+"sssss"

    }

    

   func area() -> Double {

        returnsideLength * sideLength

    }

    

   override func simpleDescription() ->String {

        return"A square with sides of length \(sideLength)."

    }

}

var square =Square(sideLength:12.2, name:"四边形")

var squareDes = square.simpleDescription()

println(squareDes)

var area:Double =square.area()//A square with sides of length 12.2.

println(area)//148.84

class EquilateralTriangle:NamedShape {

   var sideLength: Double =0.0

    

   init(sideLength: Double, name:String) {

       self.sideLength = sideLength

       super.init(name: name)

        self.numberOfSides =3

    }

   var perimeter: Double {

   get {

       return 3.0 *sideLength

    }

   set {

       sideLength = newValue / 3.0

    }

    }

   override func simpleDescription() ->String {

        return"An equilateral triangle with sides of length \(sideLength)."

    }

}

var triangle =EquilateralTriangle(sideLength: 3.1, name: "a triangle")

println(triangle.perimeter)//9.3    //执行get后花括号体，把返回值赋给对象成员变量perimeter

triangle.perimeter =9.9    //  执行set后花括号体,本花括号后面内可以使用newValue,

                            //  它代表perimeter的值, 最后把值9.9赋给perimeter。

println(triangle.perimeter)//9.9//get perimeter=sideLength

println(triangle.sideLength)//3.3